Field of the Invention
The disclosure relates in general to a semiconductor device with a memory structure, more particularly to a semiconductor device with a memory structure having a barrier-free resistance switching layer.
Description of the Related Art
Resistive random-access memory (RRAM or ReRAM) device is a non-volatile type of memory cell structure. Resistive memories attract much attention due to its simple MIM (Metal-Insulator-Metal) structure and promising scalability. Different forms of ReRAM have been disclosed, based on different dielectric materials, spanning from perovskites to transition metal oxides to chalcogenides.
Resistance switching memory cell structure, as the example of the transition metal oxide memory, is a group of two-terminal bistable memory devices that stores the data by different resistance levels. For example, a typical ReRAM device includes a tungsten (W) bottom electrode, a WSixOy memory layer, a Ti/TiN barrier layer and a TiN top electrode. The switching characteristic of the memory cell structure is very sensitive to the profile and uniformity of the bottom electrode configuration, which consequently has considerable effect on the reliability and electrical performance of the semiconductor device in practical application. It is desirable to develop a resistance switching memory cell structure with excellent structural profile and uniformity for improving the reliability and electrical properties such as great stability of data storage.